Topic: Truss model

Hi
I am a student, I am interesting in modeling the structural elements..
Now I am trying to used ATENA, its pretty easy to use it, but then I got stuck, I wonder how do you model truss system by using this ATENA2D and 3D?

I look forward to your response, Thank you

Regards

Re: Truss model

Hello, in ATENA, truss elements are only available for reinforcement (with only axial stiffness). Threaded beam elements are only available through the ATENA-GiD interface of ATENA Science. Layered shell elements are available through the Engineering 3D and Science/GiD GUEs.

Therefore, if you need to model a large truss structure in ATENA, you should probably work with ATENA Science. If you only have an Engineering licence, you can write us what you wish to model (see also Troubleshooting, 2.1.1) and maybe we can recommend a way...

Best regards.

Re: Truss model

Hi

Thanks, Of course I will try to make the model by using GiD and then I will send it to cervenka cervenka cz today to make sure there are no errors.

so far I tried GiD-ATENA Science, but everytime I ran it, I got error but the analysis was finished. the model is quite simple...

I hope you want to help me to find the error.

Thank you

Re: Truss model

Dear Sir,

I still couldn't figure it out about how to model truss system by ATENA, last time I made, it was consists a lot of errors* during analysis using ATENA Studio. I tried several times using ATENA2D as well, but I couldn't use Reinforcement material, it will give me error like "line 1 is not included in structure". could you please recommend me some other alternatives? or a tutorial (would be much appreciate).

*Note: my ATENA updated from 5.0.2 to 5.1.2.
*Errors in ATENA Studio
Warning: Principal node 13 has not been fixed while generating  macro element id: 1, name: Reinf# 1 >> # 1  type: CCDiscreteReinforcementME. (Source line: 690, file: ..\..\Sources\CCDiscreteReinforcementME\generate_elements(CCDiscreteRienforcementME).cpp, last modified at: Tue Oct  7 14:17:55 2014)
Invalid  Non-embedded macro_element_id: 1, ...and so on

Thank you.

Re: Truss model

Hello,
please keep in mind that 1-D truss elements can only be used for reinforcement in ATENA so far. To use the threaded beam elements, please see the ATENA-GiD User's Manual, 5.3.3 Beam Material.

6 (edited by myforework 2015-11-18 18:30:06)

Re: Truss model

Strut and Tie Model

meaning its not possible or what? I used it, but it keep saying that I don't have any assigned material. should I make it in 3D? so far I just try to make the truss with lines(no surface, no volume) elements connected by join.

Re: Truss model

1. Using linear design approaches typically does not make much sense with nonlinear FE analysis.
2. If you wish to use beam elements in ATENA, please follow the already referred documentation.
3. The 1-D reinforcement bar/cable elements (with only axial stiffness) are for embedded reinforcement bars/external cables. In some special situations, with additional care, they might also be used for other things (see for example Troubleshooting, 2.2.12 How can I model a pull-out experiment?), but it is not recommended in general.
4. If you have some special reasons for using the Strut and Tie approach with ATENA, or wish modelling advice from us, please explain what and why you are modelling + send us sketches etc. (Troubleshooting, 2.1.1) such that we can recommend some solution.

Re: Truss model

Hello everyone,

I'm modelling a girder strengthened in shear with CFRP. I want to use 1D springs (truss elements) with a multi linear constitutive and a large deformation formulation as interface elements. I want them to connect with one node the concrete (standard element) and with  the other node the CFRP (shell element).

To model this I drew reinforcement (defined with my multi linear constitutive) connecting concrete with CFRP. For the large deformation formulation I checked the "Geometrically nonlinear analysis" box on the global solution parameters.

I'm not sure if using reinforcement outside of elements and using them to connect a standard element with a shell element is the right way to go.

Would you suggest me others ways to model springs connecting macro elements using Atena?

I didn't use Atena springs because apparently they always need to have one node perfectly fixed and I need one node to connect to concrete (brick element) and the other to the CFRP (shell element).

Best regards.

Jose

Re: Truss model

Dear Jose,
1. it is not clear if you have already read Troubleshooting, 2.2.2 How to model carbon or glass fibre wrap (CFRP, GFRP) strengthening in ATENA?

2. To represent the connection between 1-D bars and the surrounding/adjacent material (concrete or other), please use Reinforcement Bond.

3. To represent the connection between 2 volumes, please use Interface material (Troubleshooting, 2.2.14 I have problems when using the Interface (GAP) material on contacts, and the corresponding section of the Engineering 2D or 3D or Science-GiD User's Manual).

4. Yes, you understand correctly that spring elements in ATENA are for spring supports, and not for connecting 2 elements.

5. I don't understand why you would wish to misuse 1-D reinforcement bars as a replacement for Bond or Interface elements - please explain? Moreover, I do not see any possible advantage of such modelling?

Best regards.

Re: Truss model

Hi dpryl,

Thank you very much for your quick response. I have read Troubleshooting 2.2.2 and I understand that in Atena 3D the suggests approach would be to use 3D Interface for the contact between the adjacent concrete element and CFRP shell.

However 3D Interface material is based on Mohr-Coulomb criterion and I want to implement a simpler model developed by (Sun and Ghannoum, 2015) with 1D truss elements with a constitutive calibrated to match experimental results. If you wish to check the model you can check it at: http://www.sciencedirect.com/science/ar … 181500375X

Do you think such model can be implemented using Atena? Also, is there any way to create 3D macroelements that only act as 1D trusses connecting two elements and only transmit axial stress?

Best regards,

Jose

Re: Truss model

Dear Jose,
I don't have access to the article, please send us an email (cervenka@...) with the details about your preferred model. I think it may be possible to set the ATENA Interface material model to approximate the intended behaviour...